<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .jd {
            position: relative;
            width: 120px;
            height: 249px;
            background-color: grey;
            margin: 100px auto;
        }
        .jd span {
            position: absolute;
            top: -20px;
            left: 50%;
            width: 0;
            height: 0;
            margin-left: -10px;
            border: 10px solid transparent;
            border-bottom-color: grey;
        }
    </style>
</head>
<body>
    <div class="jd">
        <span></span>
    </div>
</body>
</html>